User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

I have several e-mail accounts.
When I want to filter messages I must create a filter for every mailbox separately.
I would like to have one filter for all my e-mail accounts.
I think many users today have more than one e-mail account and have the same problem. I Googled the solution with copying filter file msgFilterRules.dat to every folder but its not elegant solution. I duplicates filters and it forces me to copy the file to several folders again after every change change. So I think global filter could be very useful solution and many users are waiting for it.

Expected results:

Maybe having one, global msgFilterRules.dat

https://support.mozilla.org/en-US/questions/1157579